For the past few weeks, I've been showing up to my sensei's class in white belt. No, it's not because I committed some great offense and was stripped of rank, nor because she's finally decided that I'm just hopeless on anything more advanced. It's because she's gone through with her hints from a few months ago and recommended me for promotion to godan, fifth degree black belt. And as part of the dan testing process in Seido Karate, students go back to white belt for a while.
The hope is that this will remind us of the importance of shoshin, "beginner's mind". Shoshin is an important idea in both Zen and in the martial arts. The idea was perhaps most famously summarized by the Soto Zen teacher Shunryu Suzuki, who wrote "In the beginner's mind there are many possibilities, but in the expert's there are few." (Suzuki Roshi is not related to D.T. Suzuki, the famous popularizer of Zen.)